In order to dispense a liquid contained in a bottle it is known to use a so called “lock down” dispensing pump which, when applied to the bottle and put on the market, is in a down-locked position.
In particular “atmospheric” dispensing pumps the housing of the dispensing pump has on its side a venting hole which function is to permit the venting, i.e. the admission of the air in the bottle. In particular during the pump actuation a volume of air enters into the bottle through the venting hole, in order to replace the liquid pumped out from the bottle by the pump.
A dispensing pump of this type is known for example from EP0990595 or WO2011/074024. When this dispensing pump is in its down-locked position, that is the condition in which the dispensing pump is supposed to be applied to the bottle and put on the market, the liquid contained into the bottle can be accumulated in some areas of the venting path. For example, with reference to the patent WO2011/074024, the housing could be filled in the area upon the piston by a certain amount of liquid that could flow through the venting hole of the housing during transportation. No preventing systems are normally considered.
So, once the dispensing pump is opened the first time, the piston pushes up this amount of liquid, so forcing it to flow out through the venting passages existing between the retaining ring and the hollow stem of the dispensing pump. The liquid can therefore go in touch with the metal spring, with a potential risk of corrosion, or even flow outside the dispensing pump, so creating unaesthetic problems, contamination of the liquid and mess.
Furthermore, the liquid that leaks out of the venting passages and stops there for a while, could also dry and clog the venting passages.